Mitsubishi Lancer (4A9 engine). Manual - part 296

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-65

STEP 7. Check the refrigerant level.
Refer to .

Q: Is the refrigerant level correct?

YES : 

Go to Step 8.

NO : 

Correct the refrigerant level (Refer to On-
vehicle Service ).

STEP 8. Replace the A/C-ECU, and then recheck 
the trouble symptom
Check that the compressor works normally.

Q: Is the check result normal?

YES : 

This diagnosis is complete.

NO : 

Replace the engine-ECU, and then register 
the ID code (Refer to GROUP 42B 
Troubleshooting 

− ID code registration 

judgement table  <Vehicles with KOS> or 
GROUP 42C Troubleshooting 

− ID code 

registration judgement table  <Vehicles 
without KOS>).

STEP 9. Connector check: A-14X A/C 
compressor relay connector

Q: Is the check result normal?

YES : 

Go to Step 10.

NO : 

Repair the connector.

STEP 10. Check the A/C compressor relay
Refer to .

Q: Is the check result normal?

YES : 

Go to Step 11.

NO : 

Replace the A/C compressor relay.

STEP 11. Voltage measurement at A-14X A/C 
compressor relay connector.
(1) Remove the relay, and measure at the relay block 

side.

(2) Voltage between terminal 2, 4 and body earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 13.

NO : 

Go to Step 12.

STEP 12. Check the wiring harness between A-
14X A/C compressor relay connector terminal 
No.2, 4 and the fusible link (38).

• Check the A/C compressor relay power supply 

line for open circuit.

Q: Is the check result normal?

YES : 

The trouble can be an intermittent 

malfunction (Refer to GROUP 00, How to 
Cope with Intermittent Malfunction ).

NO : 

Repair the wiring harness.

STEP 13. Check the wiring harness between A-
14X A/C compressor relay connector terminal 
No.3 and B-113 A/C compressor assembly 
connector terminal No.1.

• Check the A/C compressor power supply line for 

open circuit.

NOTE: Prior to the wiring harness inspection, check 
intermediate connectors A-60, and repair if neces-
sary.

Q: Is the check result normal?

YES : 

Go to Step 14.

NO : 

Repair the wiring harness.

STEP 14. Check the wiring harness between A-
14X A/C compressor relay connector terminal 
No.1 and B-39 engine-ECU connector terminal 
No.19.

• Check the A/C compressor relay power supply 

line for open circuit.

NOTE: Prior to the wiring harness inspection, check 
intermediate connectors A-11, and repair if neces-
sary.

Q: Is the check result normal?

YES : 

The trouble can be an intermittent 

malfunction (Refer to GROUP 00, How to 
Cope with Intermittent Malfunction ).

NO : 

Repair the wiring harness.

INSPECTION PROCEDURE 8: The A/C indicator flashes

COMMENTS ON TROUBLE SYMPTOM
If the A/C indicator flashes, diagnosis code B1079 
will be set (Refer to ).

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-66

INSPECTION PROCEDURE 9: A/C outlet air temperature cannot be set

Air Mixing Damper Control Motor Circuit

A/C-ECU

AIR MIXING
DAMPER
CONTROL MOTOR

Wire colour code 
B : Black     LG : Light green     G : Green     L : Blue     W : White     Y : Yellow     SB : Sky blue 
BR : Brown     O : Orange     GR : Grey     R : Red     P : Pink     V : Violet     PU : Purple     SI : Silver

AC612706

Connectors: C-13, C-117 <LHD>

AI

C-13 (B)

C-117

AC612710

Connectors: C-13, C-117 <RHD>

AW

C-13 (B)

C-117

COMMENTS ON TROUBLE SYMPTOM
If the air conditioner outlet temperature cannot be 
adjusted, the air mixing damper control motor or the 
A/C-ECU may be faulty.

NOTE: It cannot be adjusted while the engine cool-
ant temperature is low.

PROBABLE CAUSES

• Malfunction of the air mix damper control motor

• Malfunction of the A/C-ECU

DIAGNOSTIC PROCEDURE

STEP 1. Check the compressor operation
Check that the compressor operates under the fol-
lowing conditions.

• Engine operation

• Air volume control dial: Maximum

• Air conditioner switch: ON

• Temperature control dial: MAX COOL

Q: Is the check result normal?

YES : 

Go to Step 2.

NO : 

Refer to INSPECTION PROCEDURE 6: 
"The A/C compressor does not work  
<Petrol engine>", INSPECTION 
PROCEDURE 7: "The A/C compressor 
does not work  <Diesel engine>".

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-67

STEP 2. M.U.T.-III diagnosis code
Check that the diagnosis code related to the air con-
ditioner is not set.

Q: Is the diagnosis code set?

YES : 

Carry out the diagnosis code procedures. 

Refer to .

NO : 

Go to Step 3.

STEP 3. M.U.T.-III actuator test
Carry out the actuator test. (Refer to ).

• Item 06: air mixing damper control motor (Select 

"position reset").

Q: Is the check result normal?

YES : 

This diagnosis is complete.

NO : 

Go to Step 4.

STEP 4. Connector check: C-117 air mixing 
damper control motor connector, C-13 A/C-ECU 
connector

Q: Is the check result normal?

YES : 

Go to Step 5.

NO : 

Repair the connector concerned.

STEP 5. Check the wiring harness wires between 
C-117 air mixing damper control motor connector 
(terminals 3, 2, 5, 4 and 1) and C-13 A/C-ECU 
connector (terminals 29, 35, 36, 34 and 28).

• Check the input line for open circuit.

Q: Is the check result normal?

YES : 

Go to Step 6.

NO : 

Repair the wiring harness.

STEP 6. Replace the air mixing damper control 
motor, and recheck the trouble symptom.
Check that A/C outlet air temperature can be 
adjusted.
NOTE: Whenever the motor is replaced, initialise the 
motor position by using the Actuator Test.

Q: Is the check result normal?

YES : 

This diagnosis is complete.

NO : 

Replace the A/C-ECU.

INSPECTION PROCEDURE 10: Air outlets changeover is impossible.

A/C-ECU

Mode Selection Damper Control Motor  Circuit

MODE SELECTION 
DAMPER CONTROL
MOTOR

Wire colour code 
B : Black     LG : Light green     G : Green     L : Blue     W : White     Y : Yellow     SB : Sky blue 
BR : Brown     O : Orange     GR : Grey     R : Red     P : Pink     V : Violet     PU : Purple     SI : Silver

AC612706

Connectors: C-13, C-108 <LHD>

AJ

C-13 (B)

C-108

AC612710

Connectors: C-13, C-108 <RHD>

AX

C-13 (B)

C-108

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-68

COMMENTS ON TROUBLE SYMPTOM
If the air conditioner outlets changeover is impossi-
ble, the mode selection damper control motor or the 
A/C-ECU may be faulty.

PROBABLE CAUSES

• Malfunction of the mode selection damper control 

motor

• Malfunction of the A/C-ECU

DIAGNOSTIC PROCEDURE

STEP 1. M.U.T.-III diagnosis code
Check that the diagnosis code related to the air con-
ditioner is not set.

Q: Is the diagnosis code set?

YES : 

Carry out the diagnosis code procedures. 

Refer to .

NO : 

Go to Step 2.

STEP 2. M.U.T.-III actuator test
Carry out the actuator test. (Refer to ).

• Item 08: Air outlet c/o damper: (Select "position 

reset".)

Q: Is the check result normal?

YES : 

This diagnosis is complete.

NO : 

Go to Step 3.

STEP 3. Connector check: C-108 mode selection 
damper control motor connector and C-13 A/C-
ECU connector

Q: Is the check result normal?

YES : 

Go to Step 4.

NO : 

Repair the connector concerned.

STEP 4. Check the wiring harness wires between 
C-108 mode selection damper control motor 
connector (terminals 1, 4, 5, 2 and 3) and C-13 A/
C-ECU connector (terminals 33, 30, 32, 31 and 
29).

• Check the input line for open circuit.

Q: Is the check result normal?

YES : 

Go to Step 5.

NO : 

Repair the wiring harness.

STEP 5. Replace the mode selection damper 
control motor, and recheck the trouble symptom.
Check that the air outlets can be changed.
NOTE: Whenever the motor is replaced, initialise the 
motor position by using the Actuator Test.

Q: Is the check result normal?

YES : 

This diagnosis is complete.

NO : 

Replace the A/C-ECU.